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conntaxman
Power-User

Join Date: Dec 2007
Posts: 136
Good Answers: 1

LED Voltage

01/22/2011 2:18 AM

I have made some cir. for 3 watt leds and worked out well. I thinking of buying some 20 watt leds ,voltage is 13 to 18 input. amps are about 2. Could I hook these directly to a 12 auto battary? or would I have to put a resistor in the + side for control of the current.A auto battary will go to I think about 15 volts. Also I was going to put in a regular chip to make it only go to 12 vdc.

I had on 20 watt led and it said input voltage was 12/15 I think, but when I hooked it up to a car battary it worked and Bright for awhile and then went about 1/4 dim , I think because it got over heated.

Tks

John B
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aurizon
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Hobbies - HAM Radio - New Member United Kingdom - Big Ben - New Member Fans of Old Computers - Altair 8800 - New Member Canada - Member - New Member

Join Date: Jun 2006
Location: Toronto
Posts: 3968
Good Answers: 120
#1

Re: led voltage

01/22/2011 10:27 PM

high power LED MUST have proper heat sinking and current limiting. Usually the maker will give you the safe operating envelope.

Incandescent lamps simply radiate their heat away and the filament tolerates the high temperature.

The LED is a semi conductor and if it gets too hot, the mobility of dopant elements increases and the LED efficiency changes and it can stop or fuse into a metallic mass.

So google your brand for their web site and their safe operating envelope. The poser supply is usually a constant current type and the heat sink must be efficient.

Here are samples. adapt to your use.

http://www.google.ca/#hl=en&xhr=t&q=power+%2Bled+%2Binstallation&cp=23&pf=p&sclient=psy&safe=off&aq=f&aqi=&aql=&oq=power+%2Bled+%2Binstallation&pbx=1&fp=814250bde4529105

http://www.google.ca/#hl=en&xhr=t&q=power+%2Bled+%2Bpower&cp=17&pf=p&sclient=psy&safe=off&aq=f&aqi=&aql=&oq=power+%2Bled+%2Bpower&pbx=1&fp=814250bde4529105

http://www.google.ca/#hl=en&xhr=t&q=power+%2Bled+%2Bpower&cp=17&pf=p&sclient=psy&safe=off&aq=f&aqi=&aql=&oq=power+%2Bled+%2Bpower&pbx=1&fp=814250bde4529105

http://www.google.ca/#hl=en&xhr=t&q=power+%2Bled+%2Bpower&cp=17&pf=p&sclient=psy&safe=off&aq=f&aqi=&aql=&oq=power+%2Bled+%2Bpower&pbx=1&fp=814250bde4529105

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